Jque: If I own 5 shares of a stock trading at 20 cents and they have a 5 to 1 reverse split, I now own 1 share trading at $1.  What is the difference?

Mathematically, there is absolutely no difference at all. The difference is purely psychological, because a reverse split has a very negative image.

So even if you did the math and know 100 % for sure that the value of your portfolio won't change, you still might want to consider selling (early!), because others will sell and the share price will drop accordingly. It's a self-fulfilling prophecy. If all shareholder were mathematicians, nothing would happen at all.